package com.wang.leetcode;
//合并两个有序链表
public class MergeTwoLists {
     public class ListNode {
          int val;
          ListNode next;
          ListNode() {}
          ListNode(int val) { this.val = val; }
          ListNode(int val, ListNode next) { this.val = val; this.next = next; }
     }
     public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        ListNode prehead = new ListNode(0);
        ListNode pre = prehead;

        while (l1 != null && l2 != null) {
            if(l1.val <= l2.val) {
                pre.next = l1;
                l1 = l1.next;
            }
            else {
                pre.next = l2;
                l2 = l2.next;

            }
            pre = pre.next;
        }
        pre.next = l1 == null ? l2 : l1;
        return prehead.next;
    }
}
